I think I would first find myself a heathy group of subjects from wich to take blood from, killing is not my thing, and since I'll never die I would spend my life doing all those things I wouldn't do if I was a mortal, for time's too short....
Problem is, I might have to change my group of healty subjects every 10-15 years or so, you know,,, they get older

ill go jumping from building to building to get a nice view of the city....then go stalking on people at night for laughs or to SAVE them ....then go blade(you know the movie) but not in the sense that ill kill other vampire but its just that i dont want to get blood from other people(ill go blood bags/packs whatever they're called....who knows i might suck a blood from someone with HIV not that vampires could get that...right? )